Optical head

ABSTRACT

An optical head for optical recording/reading apparatus, which records and reads information with high reliability, by making use of an optical interaction with a medium in a minute area, on a high density medium revolving at high speed. It has a structure, in which an optical waveguide mechanism applies a loading force to a slider  6  receiving a buoyant force, and a system for introducing a light to the slider  6  and a system for applying the loading force are integrated into an identical body. As the result, a stable posture regulation of the slider  6  and an increase of the light intensity of irradiation on the medium can be achieved, and it becomes possible to record and read information with high reliability. Furthermore, by disposing a minute structure in the vicinity of an edge in the surface facing the medium of the slider  6 , so that the minute structure can come closer to the medium, further improvement in high density can be made.

TECHNICAL FIELD

The present invention relates to an optical head for an informationrecording/reading apparatus, in which high density information can berecorded and read by making use of an optical interaction in a minutearea on a medium to read structural or optical information formed on theminute area or record such information on the minute area.

BACKGROUND OF THE INVENTION

The development of information recording/reading apparatus using lightis evolving toward the direction of larger capacity and smaller size,and thus a higher density of recording bits has been demanded. As ameasure for achieving that, techniques using a violet semiconductorlaser or SIL (solid immersion lens) have been under study. However, inthose techniques, the improvement of recording density can be expectedto be only several times that of the existing recording denisty, becauseof the problem of diffraction limit of light. Instead of that, as atechnique that handles the optical information of such minute areabeyond the diffraction limit of light, an information recording/readingmethod making use of a near-field light is expected.

This method makes use of a near-field light, which is generated by aninteraction between a minute area and an optical aperture having a sizesmaller than the wavelength of light. This method enables the handlingof optical information in an area having a size less than the wavelengthof light, which would be beyond a limit of the conventional opticalsystem. Replaying of the optical information is performed by convertinga great amount of near-field light, which localizes on the surface ofthe recording medium by irradiating a scattering light, and is convertedinto a bound ray by the interaction with a minute aperture (collectionmode), and reading the data stored on the minute area on the medium.Furthermore, it is also possible to read by irradiating the near-fieldlight generated form a minute aperture on a surface of a medium, anddetecting the scattered light converted by the intersection with minuteunevenness on the surface of the medium, on which the information hasbeen recorded, with a detector provided separately (illumination mode).Recording is performed by irradiating a near-field light generated froma minute aperture on a surface of the recording medium to vary theconfiguration of a minute area on a medium (heat mode recording), or tovary a refractive index or transmittance of the minute area (photon moderecording). By using such a head having an optical minute aperture,which is sized less than the diffraction limit of light, the highdensity optical information recording/reading apparatus, in which thedensity of recording bits exceeds that of the conventional opticalinformation recording/reading apparatus, can be realized.

The structure of the recording/reading apparatus making use of anear-field light is almost the same as that of magnetic disc apparatus,except that a near-field light head is used instead of a magnetic head.A slider attached to the distal end of a suspension arm and providedwith an optical minute aperture optical is kept floating at a certainheight by the flying-head technology, and a desired data mark existingon a disc is accessed. In order to make the near-field light head followthe high speed revolution of the disc, a flexible-posture function isprovided for stabilizing the posture of the slider with respect to theundulation of the disc. In such a structure of a near-field light head,as the method of feeding light to the slider, means for connectingoptical fibers or an optical waveguide to the slider or arm, or meansfor irradiating a beam of laser, which is disposed horizontally to theslider or above the slider, directly on the slider has been employed.

However, when a light is incident on such a structure, since astructural body such as optical fibers or an optical waveguide isconnected between the slider and the arm, it becomes an obstacle to thefree motion of the slider, and causes the posture control of the sliderwith respect to the motion of disc to be difficult and the distancebetween the disc and the slider cannot be kept constant. As a result,the SN ratio of the output from the optical information written on thedisc is deteriorated, and there have been difficulties in writing andreading signals. Furthermore, when the signal is incident on the sliderdirectly from a laser disposed above the slider, from the necessity ofsynchronizing the incident light with the raped motion of the slider, itis required to provide an additional structural body, which can followthe motion of the slider, and it has been extremely difficult. Moreover,by providing such an additional structural body, the apparatus itselfbecomes larger in size, and it has made the recording/reading apparatusmore difficult to be miniaturized.

DISCLOSURE OF THE INVENTION

In order to solve the above-described problems, an optical head forrecording and reading information is provided which is comprised of aslider that receives a buoyant force by means of relative motion withrespect to a medium a, minute structure formed on the slider, in asurface facing the medium, for at least one of generating or detecting anear-field light, an in-slider optical waveguide mechanism formed on theslider and connected optically to the minute structure, an arm forholding the slider and applying a loading force to the slider; an in-armoptical waveguide mechansim formed on the arm for guiding a light to thein-slider optical waveguide mechanism, and an optical waveguidemechanism that contacts the in-arm optical waveguide mechansim andcontacts the in-slider optical waveguide mechanism and contacts thein-slider optical waveguide mechanism, wherein a loading force isapplied to the slider through the optical waveguide mechanism.

Furthermore, it is characterized in that the optical waveguide mechanismand the in-arm optical waveguide mechanism are formed in one unitedbody.

Furthermore, it is characterized in that the optical waveguide mechanismand the in-slider optical waveguide mechanism are formed in one unitedbody.

Furthermore, it is characterized in that an area where the opticalwaveguide mechanism contacts the in-arm optical waveguide mechanism oran area where the optical waveguide mechanism contacts the in-slideroptical waveguide mechanism or both areas of those are extremely small.

Still furthermore, it is characterized in that the optical waveguidemechanism contacts the in-arm optical waveguide mechanism or thein-slider optical waveguide mechanism or both of those, at one point.

According to the present invention, it is possible that the light fromthe arm side is transmitted to the slider with certainty and, at thesame time, the obstacle to the free motion of the slider, which would becaused by the structural body that guides a light to the slider, iseliminated, and the posture of the slider is controlled freely inresponse to the motion of the medium, while keeping the distance betweenthe medium and the slider scanning on the medium constant. As a result,signals can be input and output with a high SN ratio and stability.Moreover, since the optical waveguide mechanism that transmits a lightand the slider are minute structural bodies, which are produced by amicro-machining process using silicon or the like, the suspensionfunction of the arm is not obstructed and the overweight nature of theslider has no influence on its motion. Accordingly, the entire apparatuscan be miniaturized. Moreover, since the entire optical head or at leasta great portion thereof is produced by a mass production line withsemiconductor processes, its cost can be made lower.

Furthermore, an optical head is characterized in that the opticalwaveguide mechanism has a part shaped like a cone or a hanging bellhaving a pointed top, and contacts at the part.

Furthermore, it is characterized in that the optical waveguide mechanismhas a part shaped as a part of spherical surface and contacts at thepart.

Furthermore, it is characterized in that the optical waveguide mechanismhas a part having a condensing function.

By making the optical design of the optical waveguide according to thepresent invention, it is possible that a light is transmitted to theslider with certainty and a large amount of light is supplied to theslider. Furthermore, by adjusting the spherical shape, the conical shapeor the refractive index of the optical waveguide, it is possible tocollect more light around a minute aperture formed in the slider forgenerating a near-field light. As the result, signals can be input andoutput with a high SN ratio, and an apparatus having a high reliabilitycan be produced.

Moreover, an optical head is characterized in that the loading force isapplied toward the center of gravity of the slider, and the minutestructure that exists in a surface facing the medium is positioned on astraight line, which links the point the slider receives the loadingforce with the center of gravity.

Furthermore, it is characterized in that the minute structure ispositioned in the vicinity of an edge of a surface facing the medium,depending on the shape of the slider or its density distribution or thecombination of those.

Furthermore, it is characterized in that there exists a recess having asize corresponding to ⅕ or more of the volume of the slider, at aportion in a surface opposite to the surface facing the medium of theslider.

Furthermore, it is characterized in that there exists a difference inthickness having a differential level corresponding to {fraction (1/10)}or more of the averaged thickness of the slider, in a surface facing themedium of the slider.

Still furthermore, it is characterized in that a material having adensity different from that of the slider occupies {fraction (1/10)} ormore of the total volume of the slider.

According to the present invention, although the posture of the floatingslider inclines slightly with respect to the medium surface, due to anair pressure distribution that the surface facing the medium of theslider receives by the high speed motion of the medium, the aperture canbe disposed at a region close to the medium in the surface facing themedium of the slider, and thereby further more minute recording andreading becomes possible. Moreover, by bringing the aperture closer tothe medium, SN ratio in recording and reading can be improved, and aninformation recording/reading apparatus having high stability andreliability can be produced. Furthermore, resulting from the improved SNratio, a high-speed recording/reading becomes possible without anecessity of the large-powered light source, and thereby a small-sized,thin type and low-priced information recording/reading apparatus can beproduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a rough sketch showing an example of the opticalstoring/reading apparatus according to the embodiment 1 of the presentinvention.

FIG. 2 is a diagram showing a structure of the optical head according tothe embodiment 1 of the present invention.

FIG. 3 is a diagram-showing a structure of the optical head according tothe embodiment 2 of the present invention.

FIG. 4 is a diagram showing a structure of the optical head according tothe embodiment 3 of the present invention.

FIG. 5 is a diagram showing a structure of the optical head according tothe embodiment 4 of the present invention.

FIG. 6 is a diagram showing a structure of the optical head according tothe embodiment 5 of the present invention.

FIG. 7 is a diagram showing a structure of the optical head according tothe embodiment 6 of the present invention.

FIG. 8 is a diagram showing a positional relationship between theoptical head and the medium, according to the embodiment 6 of thepresent invention.

FIG. 9 is a diagram showing a structure of the optical head according tothe embodiment 6 of the present invention.

FIG. 10 is a diagram showing a structure of the optical head accordingto the embodiment 7 of the present invention.

FIG. 11 is a diagram showing a structure of the optical head accordingto the embodiment 7 of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1

FIG. 1 shows a rough sketch of an example of the optical storing/readingapparatus according to the embodiment 1 of the present invention. On adisc 1 (medium) revolving at high speed, a slider 2 is provided which iskept at a certain distance from the disc 1 by a buoyant force producedby the hydrodynamic motion generated by the revolution and a loadingforce produced by the arm 3. The slider 2 is held at the distal endportion of the arm 3, and can scan to a desired position on the disc 1by moving horizontally the arm 3 about a rotation axis 4 coupled with amotor. The light propagated an optical waveguide 5 on the arm 3 passesthrough an optical waveguide in the slider 2, is converted into anear-field light by a minute aperture formed in a surface facing a discof the slider 2, and is irradiated on the disc 1. Scattered lightgenerated by the interaction between this near-field light and a minutearea on the surface of the disc 1 is converted into an electric signalby a light sensing device disposed within or near the slider 2, andsupplied to a signal processing circuit, where the information of theminute area is read.

FIG. 2 shows a structure of the optical head according to the embodiment1 of the present invention. The optical head 100 of this structure iscomposed of: a slider 6 having a minute aperture 8 and an in-slideroptical waveguide 7 is formed therein; a holding member 14 for holdingthe slider 6; an in-arm optical waveguide 11 including a weightingmember 12 for applying a loading force to the slider 6; and an arm 10,in which the in-arm optical waveguide 11 is formed. The slider 6 isdisposed close to the distal end of the arm 10 and under the arm 10.Although the in-arm optical waveguide 11 is formed on top of the arm 10in FIG. 2, it may be also formed in the arm 10 or under the arm 10.

The light to be irradiated on the medium propagates through the in-armoptical waveguide 11 formed on the arm 10, and is guided to above theslider 6. Above the slider 6, a light reflector surface 13 fordeflecting the direction of light propagation, is formed at a portion ofthe in-arm optical waveguide 11, so that the light guided to above theslider 6 is deflected in its direction and is further guided to thein-slider optical waveguide 7 formed in the slider 6. At that time, thelight propagates through a protruded weighting member 12, which isformed of a portion of the in-arm optical waveguide 11 and applying aloading force to the slider 6. By adjusting the light refractive index,the taper angle of sloping surface and the shape of protrusion of theweighting member 12, the light, which propagated through the in-armoptical waveguide 11, was reflected by the light reflector surface 13and spread, is condensed, and introduced into the in-slider opticalwaveguide 7. In the slider 6, which is connected with the arm 10 via theholding member 14, there exists an inverse-cone shaped hole having aminute aperture 8 for detecting and generating a near-field light at thevertex of the conical shape of the hole, and the in-slider opticalwaveguide 7 is embedded within the hole. The light, which has beenintroduced into the in-slider optical waveguide 7 via the weightingmember 12, is condensed around the minute aperture 8, by the effect of alight reflecting surface 9 formed within the inverse-cone shaped holewith surrounding the in-slider optical waveguide 7. The condensed lightis converted into a near-field light by passing through the minuteaperture 8, and irradiated on a minute area formed on the medium.Although the above description has been made for the illumination mode,it can be also applied similarly to the collection mode, in which thenear-field light is detected, and similar effect can be obtained.

The slider 6 receives a buoyant force from the medium side, by thehydrodynamic motion of air generated by the high speed revolution of themedium. By applying a loading force from the arm 10 having a suspensionfunction to the slider 6 receiving the buoyant force, the distancebetween the medium and the minute aperture 8 for causing an interactionof near-field light can be kept in a constant level, and therebyrecording and reading the accurate information can be performed based onthe intensity distribution of the near-field light generated by theaperture. The slider 6 must be continually regulated in a proper posturein response to the undulation of medium surface, to keep its relativeposition constant, and it is an effective method to make the slider 6adapt to the motion of medium by applying the loading force at one pointon the center of gravity. In the embodiment 1 according to the presentinvention, the weighting member 12 for applying the loading force isformed of a portion of the in-arm optical waveguide 11. The weightingmember 12 is pressing the center of gravity of the slider 6 with thepointed vertex of the inverse-cone shaped protrusion, so that the slider6 can be always regulated in a proper posture with respect to the motionof medium, and, at the same time, is also playing a role of guiding thelight from the arm 10 side to the slider 6 side. For the purpose ofthat, even if the slider 6 moved its position slightly for adjusting itsposture, the relative position between the in-arm optical waveguide 11pressing the gravity center of the slider and the in-slider opticalwaveguide 7 being pressed is always the same, and thereby a stable andconstant amount of light can be supplied.

The arm and the slider composing such a structure can be produced by themicro-machining process that is represented by that of silicon. In thecase of the slider, for example, the inverse-conical hole can be formedon a silicon substrate, which is the parent body of the slider, by ananisotropic etching method, and an optical minute aperture is formed atthe vertex thereof. A laminated layer of an optical waveguide materialfor guiding the light to the aperture is produced, by laminating ahigh-reflectance material inside the hole. On the other hand, in thecase of the arm, a material to be the optical waveguide is formed on ametal material, which have been formed so as to have a shape of the arm,and, by etching or by exposing and developing in a manner ofphoto-lithographic technique, a desired shape of the optical waveguideis produced. As described above, by making use of such a micro-machiningprocess that is represented by the semiconductor industry, massproduction is made easier, and thereby the miniaturization and massproduction of the slider and the arm can be easily realized. Moreover,by further adding the improvement in the higher density of recordingbits and in the smaller diameter of discs, the miniaturization and thelighter weight of the optical recording/reading apparatus can berealized.

As described above, in the optical head according to the embodiment 1,although it has a simple structure, it is possible that the posture ofthe slider is controlled freely according to the undulation of the discsurface, in response to the motion of medium revolving at a high speed,by forming the weighting member for applying a loading force to theslider with a portion of the optical waveguide, and that the distancebetween the disc and the slider is kept constant. At the same time, astable and constant amount of light can be continually supplied from theminute aperture, by arranging the relative position between the in-armoptical waveguide and the in-slider optical waveguide to be constant.Moreover, as the effect by the configuration given to the opticalwaveguide or the effect of condensing light by adjusting the refractiveindex, sufficient amount of light can be supplied from the minuteaperture to the medium, and thereby stable recording and reading thesignals having a high SN ratio can be realized.

Embodiment 2

FIG. 3 shows a structure of the optical head according to the embodiment2 of the present invention. The optical head 200 of this structure iscomposed of: a slider 6 having a minute aperture 8 and an in-slideroptical waveguide 7, which is provided with a weight-receiving member 15at a portion, is formed therein; a holding member 14 for holding theslider 6; an in-arm optical waveguide 11 for applying a loading force tothe slider 6; and an arm 10, in which the in-arm optical waveguide 11 isformed. Although the rough structure is similar to the embodiment 1, itis characterized in that a projection for receiving the loading forcefrom the in-arm optical waveguide 11 is formed on the in-slider opticalwaveguide 7. Also in FIG. 3, the in-arm optical waveguide 11 may beformed anywhere of the arm 10, i.e., on top of, in or under the arm 10,similarly to FIG. 2.

The weight-receiving member 15 formed of a portion of the in-slideroptical waveguide 7 is shaped conical, and contacts the in-arm opticalwaveguide 11 at the vertex of the cone. The light, which has beenreflected by the light reflector surface 13 and is to be transmittedtoward the slider 6, comes incident on the weight-receiving member 15formed of a portion of the in-slider optical waveguide 7, with keepingstability, and is guided to the minute aperture 8. Similarly to theembodiment 1 by adjusting the incident angle to the weight-receivingmember 15 and its refractive index, the light incident on the in-slideroptical waveguide 7 can be condensed to the minute aperture 8. Thevertex of projection of the weight-receiving member 15 is positionedabove the gravity center of the slider 6, and the posture of the slider6 can be freely controlled on its posture correspondingly to the motionof the medium revolving at high speed, and thereby the distance betweenthe medium and the slider 6 can be kept constant. According to such aconfiguration, the recording and reading with stable signals can beperformed with high reliability.

Embodiment 3

FIG. 4 shows a structure of the optical head according to the embodiment3 of the present invention. Although the optical head 300 of thisstructure is similar to the embodiment 1, it is characterized in that aportion of the in-arm optical waveguide 11 has a hemispherical shape,the portion being a weighting member 16. As a result, since more lightcan be condensed to be supplied to the minute aperture 8 by the lenseffect of the hemispherical shape, more light can be irradiated on therecording medium. Also in the optical head 300 of this structure, sincea point of the spherical body contacts the in-slider optical waveguide 7and applies a loading force to it, the slider 6 can respond freely tothe motion of the medium and keep the relative distance to the mediumconstant. Accordingly, since the relative positions of the arm 10 andthe slider 6 do not vary, the light from the arm 10 side can be suppliedconstantly. As a result, the SN ratio of the light signal is furtherimproved and an apparatus having high reliability can be produced. Alsoin FIG. 4, the in-arm optical waveguide 11 may be formed anywhere of thearm 10, i.e., on top of, in or under the arm 10.

Moreover, as in FIG. 3 showing the embodiment 2, the spherical shapeformed of a portion of the optical waveguide may be formed on thein-slider optical waveguide 7 instead, though not shown in figure. Alsoin this case, it has the same effect and an apparatus having highreliability can be produced.

Embodiment 4

FIG. 5 shows a structure of the optical head according to the embodiment4 of the present invention. Although, in the embodiments 1 through 3, aprotrusion or a partial sphere is formed either on the in-slider opticalwaveguide or on the in-arm optical waveguide, in the optical head 400shown in the embodiment 4, there exist those members provided on bothsides, such as a weighting member 17 formed on the in-arm opticalwaveguide 11 and a weight-receiving member 18 formed on the in-slideroptical waveguide 7, respectively, and those members are contacting eachother. Although those members are shown as hemispheres in FIG. 5, theymay be replaced by protrusions, of course. Moreover, it may beconfigured such that the one is a hemisphere and the other is aprotrusion. In this case, the lens effect of the hemispherical shape isfurther amplified and more amount of light can be condensed to theminute aperture 8. As the result, since the quantity of near-field lightgenerated by the aperture can be increased, more improvement in SN ratiocan be expected. Since it is a matter of course that the slider 6 isreceiving the loading force at one point, similarly to the above, a freeposture control can be conducted, and an apparatus having the structurewith high reliability in the light signals can be realized, by thesupply of stable light given by the contact between both the opticalwaveguides and by the effect of light-condensing by a lens effect. Alsoin FIG. 5, the in-arm optical waveguide 11 may be formed anywhere of thearm 10, i.e., on top of, in or under the arm 10, similarly to the above.

Embodiment 5

FIG. 6 shows a structure of the optical head according to the embodiment5 of the present invention. In an optical head 500, an inverse-conicalhole is formed on a silicon substrate, which is the parent body of theslider 6, so that a minute aperture 8 comes to the vertex of the conicalhole. A function of condensing light on the minute aperture 8 isprovided by forming a light-reflecting layer 9 inside the hole. Insidethe conical hole, a spherical lens 19 is inserted, and a loading force,which is given by the in-arm optical waveguide 11, is applied to theslider 6. Although the spherical lens 19 contacts with the inner wall ofthe hole in the slider and the in-arm optical waveguide, respectively,it can revolve freely and thereby enables the slider 6 to vary itsposture with following the motion of the medium, and, with theflying-head technology, the slider 6 can be always kept in a certainrelative position with respect to the medium.

Furthermore, by a lens effect of the sphere, much amount of light can becondensed on the minute aperture 8, and in turn, much amount of lightcan be irradiated from the minute aperture 8 on the medium.Consequently, since the signal level is stabilized by keeping uniformlythe distance from the near-field light having a light intensitydistribution, and SN ratio is improved by increasing the lightintensity, an optical storing/reading apparatus having high reliabilitycan be realized.

Embodiment 6

FIG. 7 shows a structure of the optical head according to the embodiment6 of the present invention. The optical head 600 of this structure issimilar to the optical head 100 of the embodiment 1 shown in FIG. 2,except that the slider 6 has a surface opposing to the medium (surface22 facing the medium), which is recessed partly with leaving a protrudedportion 20 an the trailing edge side of the slider 6. The thickness ofthe slider 6 at the position where the slider 6 is connected with thearm 10 via the holding member 14 (thickness of the protruded portion 20)is thinner than that of the slider 6 at the position where the loadingforce is applied via the weighting member 12. The weighting member 12 isapplying a loading force is applying a loading force at the pointpushing the gravity center of the slider 6, so that the slider 6 canalways keep a certain relative position according to the undulation ofmedium. The light, which has propagated through the in-arm opticalwaveguide 11 and was reflected by the light reflector surface 13,propagates to the minute aperture 8 through the weighting member 12. Forthe purpose of this, the position of the minute aperture 8 is determinedto be a point nearly close to the gravity center in the surface 22facing the medium. In the optical head 600 according to the embodiment6, the gravity center of the slider 6 shifts by cutting a part of thesurface 22 facing the medium of the slider 6, and thereby the minuteaperture 8 comes closer to the trailing edge side of the surfaceadjacent to the medium (surface 22 facing the medium). By adjusting theshape of the slider 6 in this manner, the minute aperture 8 can bedisposed at desired position on the surface opposing to the medium(surface 22 facing.the medium). Here, the ratio of the thickness of theprotruded portion 20 to that of the slider 6 at the minute aperture mustbe {fraction (9/10)} or less, so that the slider 6 does not have aninfluence on the air flow when the slider 6 is floating above themedium, or that the aperture can be brought close to the medium, withpreventing a part of the protruded portion 20 from hitting the medium.

FIG. 8 shows a positional relationship of the slider 6 with respect tothe medium 21, when the optical head 600 according to the embodiment 6of the present invention is scanned over the medium 21 revolving at highspeed. Although the slider 6 receives a buoyant force by thehydrodynamic motion of air when the medium 21 revolves at high speed, itis possible to keep the distance from the surface of the medium 21constant, by applying a loading force from the arm 10 to the slider 6.The posture of the slider 6 under such a situation is shown in FIG. 8.When the medium 21 runs in a direction shown by outlined arrows in FIG.8, air flow is generated between the medium 21 and the slider 6 in thedirection shown by solid arrows in FIG. 8. At the entrance, the surface22 facing the medium receives a strong pressure toward the directionperpendicular to the medium, and the gap from the medium 21 is expandedat the leading edge of the slider 6. This causes the slider 6 toincline, and, at the exit of the air flow at the trailing edge of theslider 6, the distance between the surface 22 of the slider 6 facing themedium and the medium 21 becomes a minimum value. Since the minuteaperture 8 is formed closer to the trailing edge at the area where thedistance from the medium 21 is small, the minute aperture 8 comes closerto the medium 21, an SN ratio of the signal is improved and a highdensity read of information becomes possible. Assuming that the surface22 facing the medium of the slider 6 has a size of 1 mm square and theminute aperture 8 is disposed within a range 0.4 mm or less from theedge of the surface 22 facing the medium of the slider 6, by employingthe shape as in FIG. 7, where the protruded portion 20 is formed on theside of the slier, the gravity center of the slider 6 is shifted, andthereby, the minute aperture 8, which is disposed closer to the edge ofthe surface 22 facing the medium, comes to a point that is closer to themedium 21 when the medium revolves at high speed. It results animprovement of SN ratio, and an information recording apparatus furtherimproved in high density, large capacity and small size can be realized.

FIG. 9 shows another example of the optical head 700 according to theembodiment 6 of the present invention. FIG. 9 is showing an optical head700, in which the large part of the slider 6 is cut off to shift thegravity center of the slider 6. Although the slider 6 may be configuredso as to dispose the minute aperture 8 at the edge of the surfaceopposite to the medium (surface 22 facing the medium), by cutting offthe large part of the surface, as shown in FIG. 7, it may be alsoconfigured so as to dispose the minute aperture 8 at the end of thesurface 22 facing the medium, by forming a large recess 23 in thesurface opposite to the surface 22 facing the medium of the slider 6 toshift the gravity center of the slider 6, as shown in FIG. 9. In thiscase, by forming the recess 23 at the region that does not have aninfluence on the air flow during the high speed revolution, a stablefloating height from the medium can be ensured, and there by an opticalrecording apparatus having high SN ratio and excellent reliability canbe produced. Here, in order to bring the minute aperture 8 sufficientlyclose to the medium, the position of the minute aperture must be shiftedfrom the center toward the end by at least {fraction (1/10)} of thelength of the surface 22 facing the medium. Accordingly, the dimensionsof the recess 23 should be selected to be ⅕ or more of the volume of theslider 6.

Embodiment 7

FIG. 10 shows a structure of the optical head 800 according to theembodiment 7 of the present invention. This optical head 800 has astructure similar to the optical head 600 of the embodiment 6 shown inFIG. 7, except that a protruded portion 24 is formed of a materialdifferent from that composing the slider 6. For example, when thematerial composing the slider 6 is Si group or SiO₂ group, the protrudedportion 24 may be formed of metal or epoxy group material. Since thedensity of different material will be different, the minute aperture 8,which is positioned close to the gravity center of the slider 6, comesto the edge in the surface 22 facing the medium, and thereby thedistance from the medium can be made closer. Accordingly, the effectsimilar to that of the embodiment 6 can be obtained.

Furthermore, the different material is not necessarily protruded, but itmay be formed at a portion within the slider 6 as shown in FIG. 11. Whenthe density of the different material 25 is higher than that of thematerial composing the slider 6, the minute aperture 8, which ispositioned close to the gravity center, comes away from the center ofthe surface 22 facing the medium, and thereby the minute aperture 8 canbe disposed in an area, where the distance from the medium is shorter.For example, if the main material of the slider 6 is Si, then thisdifferent material 25 may be copper, SUS, gold or the like, the densitythereof is higher than that of Si. Contrary to that, even if an epoxymaterial, which has a density lower than that of Si, is used, theposition of the minute aperture 8 can be shifted because of deviation ofthe gravity center.

Although, in the embodiments 6 and 7, the structure of the optical headhas been described to be the optical head 100 according to theembodiment 1 shown in FIG. 2 as an example, it should not be limited tothe optical head 100, but the structure may be any of the optical head200 shown with the embodiment 2, the optical head 300 shown with theembodiment 3, the optical head 400 shown with the embodiment 4, and theoptical head 500 shown with the embodiment 5.

Industrial Applicability

As described heretofore, according to the present invention, thestructure is formed so that the slider can move freely in correspondencewith the medium revolving at high speed to keep the distance between themedium and the slider always constant, and the intensity of thenear-field light, which is generated by the minute aperture formed inthe slider, is stabilized to be uniform. Accordingly, stable recordingand reading of the information signals with using light can be realized,without the influence by the intensity distribution of the near-fieldlight. Moreover, since a light condensing function is provided in theoptical waveguide, a recording/reading method giving a high SN ratio andbeing excellent in reliability becomes possible. Furthermore, since thealmost all components of the optical head according to the embodimentcan be produced by micro-machining process with using Si or the like,the miniaturization of the entire apparatus can be achieved, and, at thesame time, the cost reduction by the applicability of mass productioncan be realized.

Additionally, since the aperture can be disposed at an area, which iscloser to the medium, within the surface facing the medium, withoutobstructing the free motion of the slider, SN ratio of signals isimproved and thereby the stability and reliability of products can beimproved. Moreover, by utilizing of a smaller aperture, reading from andwriting to more minute areas can be carried out, and thereby theimprovement in resolution and in high density information becomespossible. Furthermore, since, even if the power of light source isreduced, reading at a sufficiently high speed is possible, theminiaturization, thinned configuration and cost reduction of productscan be achieved.

What is claimed is:
 1. An optical head for recording and readinginformation, comprising: a slider that receives a buoyant forcegenerated by undergoing relative motion with respect to a recordingmedium; a minute structure provided in a surface of the slider facingthe recording medium for at least one of generating a near-field lightor detecting a near-field light; an in-slider optical waveguidemechanism formed in the slider and connected optically with the minutestructure for conveying light between the slider and the minutestructure; an arm for holding the slider in close proximity to therecording medium and applying a loading force to the slider tocounterbalance the buoyant force generated in response to the relativemotion; an in-arm optical waveguide mechanism formed on the arm forguiding a light from the arm to the in-slider optical waveguidemechanism; and an optical waveguide mechanism in optical and mechanicalcontact with the in-arm optical waveguide mechanism and the in-slideroptical waveguide mechanism, the loading force being applied to theslider through the optical waveguide mechanism.
 2. An optical headaccording to claim 1; wherein the optical waveguide mechanism and thein-arm optical waveguide mechanism are an integral body.
 3. An opticalhead according to claim 1; wherein the optical waveguide mechanism: andthe in-slider optical waveguide mechanism are an integral body.
 4. Anoptical head: according to any one of claims 1 through 3; wherein atleast one of the areas of the optical waveguide mechanism that are incontact with the in-arm optical waveguide mechanism and the in-slideroptical waveguide mechanism is extremely small.
 5. An optical headaccording to claim 1; wherein the optical waveguide mechanism contactsthe in-arm optical waveguide mechanism at one point and contacts thein-slider optical waveguide mechanism at a different point.
 6. Anoptical head according to claim 1; wherein the optical waveguidemechanism extends from the slider mechanism, is shaped as a cone or ahanging bell having a pointed top, and contacts the in-arm opticalwaveguide mechanism at the pointed top thereof.
 7. An optical headaccording to claim 1; wherein the optical waveguide mechanism extendsfrom the slider mechanism, is shaped as part of a sphere, and contactsthe in-arm optical waveguide mechanism at a part of the sphericalsurface.
 8. An optical head according to claim 1; wherein the opticalwaveguide mechanism has a light condensing function.
 9. An optical headaccording to claim 1; wherein the loading force is applied toward acenter of gravity of the slider, and the minute structure provided inthe surface facing the recording medium is disposed on a straight linewhich links a point at which the slider receives the loading force withthe center of gravity of the slider.
 10. An optical head according toclaim 9; wherein a shape, a density or a combination of the shape anddensity of the slider is determined so that the minute structure isdisposed closer to an edge of the surface facing the recording medium.11. An optical head according to claim 10; further comprising a recessprovided in the slider, the recess having a volume of ⅕ or more of avolume of the slider and being formed in a surface of the slideropposite the surface of the slider facing the recording medium.
 12. Anoptical head according to claim 10; wherein a surface of the sliderfacing the recording medium has a difference in thickness of at least{fraction (1/10)} of an averaged thickness of the slider.
 13. An opticalhead according to claim 10; wherein a material having a densitydifferent from that of a remainder of the slider occupies {fraction(1/10)} or more of a total volume of the slider.
 14. An optical headaccording to claim 1; wherein the optical waveguide mechanism extendsfrom the arm, is shaped as a cone or a hanging bell having a pointedtop, and contacts the in-slider optical waveguide mechanism at thepointed top thereof.
 15. An optical head according to claim 1; whereinthe optical waveguide mechanism extends from the arm, is shaped as partof a sphere, and contacts the in-slider optical waveguide mechanism at apart of the spherical surface.
 16. An optical head for at least one ofrecording and reading data, comprising: a slider spaced by a small gapfrom a recording medium during use of the optical head for readingand/or writing data on the recording medium, the small gap beingprovided by a buoyant force produced when the slider undergoes relativemotion with respect to the recording medium; a minute aperture formed ina surface of the slider facing the recording medium for at least one ofgenerating or scattering near-field light; an in-slider opticalwaveguide formed in the slider for conveying light therethrough to orfrom the minute aperture; an arm for holding the slider in closeproximity to the recording medium and applying a loading force to theslider to counterbalance the buoyant force generated in response to therelative motion; an in-arm optical waveguide formed on the arm forguiding light from the arm to the in-slider optical waveguide; a holdingmember for attaching the slider to the arm; and an optical waveguidemechanism in optical and mechanical contact with the in-arm opticalwaveguide and the in-slider optical waveguide for conveying lightbetween the in-arm optical waveguide and the in-slider optical waveguideand applying the loading force to the slider.
 17. An optical headaccording to claim 16; wherein the optical waveguide mechanism extendsfrom the arm and has a conical shape with a sharpened tip, the tip beingin contact with the in-slider optical waveguide.
 18. An optical headaccording to claim 17; wherein the optical waveguide mechanism condenseslight from the arm and projects the condensed light to the in-slideroptical waveguide.
 19. An optical head according to claim 17; whereinthe optical waveguide mechanism expands light from the in-slider opticalwaveguide and projects the expanded light to the in-arm opticalwaveguide.
 20. An optical head according to claim 16; wherein theoptical waveguide mechanism extends from the arm, has a portion providedwith a spherical shape, and is in contact with the in-slider opticalwaveguide at the portion having the spherical shape.
 21. An optical headaccording to claim 20; wherein the optical waveguide mechanism condenseslight from the arm and projects the condensed light to the in-slideroptical waveguide.
 22. An optical head according to claim 20; whereinthe optical waveguide mechanism expands light from the in-slider opticalwaveguide and projects the expanded light to the in-arm opticalwaveguide.
 23. An optical head according to claim 16; wherein theholding member connects the slider to the arm at a trailing edge sidethereof, and the slider has a larger thickness at a leading edge sidethereof than at the trailing edge side thereof so that when the sliderundergoes relative motion with respect to the recording medium, a torqueproduced by the buoyant force does not cause the trailing edge side ofthe slider to come into contact with the recording medium.
 24. Anoptical head according to claim 23; wherein the minute aperture isformed closer to the trailing edge side of the slider than to theleading edge side thereof so that the minute aperture is urged closer tothe recording medium by the torque.